Epoxy Resin Curing Agent with Clathrate Compound
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Solution Overview
Problem
Current epoxy resin compositions for electrical insulation systems face challenges due to the impending restriction of anhydride use, as they are labeled as respiratory sensitizers, and amine curing agents result in uncontrolled exotherm and inappropriate cure profiles, leading to degradation of mechanical properties and thermal issues.
Innovation Solution
A thermosetting epoxy resin composition using a curing agent comprising sterically hindered aromatic diamines and a clathrate compound formed by reacting a tetrakisphenol with an imidazole or imidazolium derivative, which provides a long pot life, high reactivity, and controlled cure profile, eliminating the need for anhydrides and reducing toxicity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If anhydrides are used as curing agents for epoxy resins, then good mechanical and electrical properties are achieved, but respiratory sensitivity issues arise leading to regulatory restrictions
Solution Approach 1:
The patent removes the harmful anhydride curing agent from the epoxy resin system and replaces it with alternative curing agents (amines, polyamines, or amino acid derivatives) that do not cause respiratory sensitivity issues, thereby eliminating the harmful factor while maintaining the desired mechanical and electrical properties
Solution Approach 2:
The patent changes the chemical parameter of the curing agent from anhydride to amine/polyamine/amino acid derivative, fundamentally altering the curing mechanism and chemical composition to eliminate respiratory sensitivity while preserving performance characteristics
2Duration of action of moving object
If amines are used as curing agents for epoxy resins, then pot life is extended, but uncontrolled exotherm occurs leading to degradation of mechanical properties
Solution Approach 1:
The patent modifies the reactivity parameter of the amine curing agent by selecting specific types (aromatic amines, polyamines, or amino acid derivatives) and adjusting their molecular structure and functionality to reduce curing speed and exotherm while maintaining adequate pot life
Solution Approach 2:
The patent uses composite curing systems combining amine/polyamine with amino acid derivatives or uses blended amine formulations to balance pot life extension with exotherm control, achieving synergistic effects that neither component could achieve alone
3Object-affected harmful factors
If aromatic amines/polyamines are used as curing agents, then toxicity is reduced compared to anhydrides, but pot life and reactivity become inappropriate for electrical applications
Solution Approach 1:
The patent adjusts the reactivity and pot life parameters by selecting specific aromatic amine/polyamine structures and combining them with amino acid derivatives to achieve optimal balance between low toxicity and appropriate processing time for electrical applications
Solution Approach 2:
The patent creates composite curing systems using combinations of aromatic amines/polyamines with amino acid derivatives to fine-tune both the toxicity profile and the pot life/reactivity characteristics, achieving a balanced formulation suitable for electrical insulation applications
4Speed
If accelerators are added to aromatic amine/polyamine compositions, then reactivity is increased, but pot life is shortened making the composition unsuitable for various applications
Solution Approach 1:
The patent modifies the reactivity parameter directly by selecting amino acid derivatives with appropriate curing speeds and combining them with aromatic amines/polyamines to achieve the desired balance between reactivity and pot life, eliminating the need for separate accelerators that would excessively shorten pot life
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The composition achieves R42-free and SVHC-free epoxy resin systems with improved mechanical, electrical, and dielectrical properties, suitable for applications like switchgears and transformers, with a controlled cure profile and enhanced thermal stability.
Implementation Method 1
a clathrate compound obtained by reacting a tetrakisphenol of the formula (1) or a 9,9-Bis(4-hydroxyphenyl)fluorene of formula (2) as the host molecule and an imidazole or an imidazolium derivative as the guest molecule
Implementation Method 2
at least one aromatic amine containing at least two amino groups
Data Source
AI summary
The invention relates to a curing agent for thermosetting epoxy resins comprising (a) at least one aromatic amine containing at least two amino groups, and (b) at least one clathrate compound obtained by reacting a tetrakisphenol of the formula (1), or a 9,9-Bis(4-hydroxyphenyl)fluorene of formula (2), as the host molecule, and an imidazole or an imidazolium derivative as the guest molecule, wherein the substituents are as defined in the description, and n is the number 0, 1, 2 or 3, which can advantageously be used for the curing of epoxy resins. In addition, the invention also relates to a process for the preparation of a cured article, a process for the preparation of insulation systems for electrical engineering and a cured article obtained by the processes.